Polyolefinic acids, particularly polyacrylic acids, grafted with polyglycolethers and monomethylpolyglycolethers (MPEG) and their use as super-plasticizers are well known from literature. They provide high fluidity to high-strength cement and concrete compositions combined with an extremely low water-to-cement or concrete ratio. In addition they reduce the decrease in fluidity, which takes place after a certain time, and control the generation of foam during the making of the final preparations. Examples for the state of the art can be found inter alia in FR 2776285 B1 (Chryso), EP 1260536 A1 (BASF) or WO 97/039037 A1 (Mbt). Usually, manufacture of the grafted polymers takes place in two steps: firstly, the free-radical polymerization is carried out in water, and then the esterification is conducted. Of course, prior to esterification the water has to be removed, which makes the process time-consuming and not very efficient.
In this context, reference is also made to international patent application WO 06/050850 A1 (Cognis) disclosing anionic polymers useful as super-plasticizers for concrete, which are obtained by polymerization of (meth)acrylic acid or their esters with dipropylendiglycolacrylate (DPGDA), tripropylenglycoldiacrylate (TPGDA), acrylamidomethyl propanesulfonic acid (AMPS) and/or acryl acetate (AA) and subsequent treatment of the intermediates with mixtures of short- and long-chain alkylpolyalkyleneglycols. Another group of concrete plasticizers obtained from the polymerization of maleic acid (anhydride) and (meth)acrylic acid is known from EP 1319676 A1 (Cognis). Polyacrylic acids grafted by polyethyleneglycols and their use as superplasticizers for concrete is also known from EP 1396506 A1 (Cognis). Finally, WO 97/39037 A1 (Sandoz) describes the use of a styrene/maleic acid anhydride co-polymer, post-esterified with a mono-methoxy polyglycol ether for the same purpose; the maleate moiety, however, has a symmetric structure. Nevertheless, none of the polymers known from the state of the art simultaneously fulfil all requirements of the proposed application.
Therefore, the present invention is directed to providing novel polymers with improved super-plasticizing and retarding properties in order to overcome the disadvantages known from the state of the art. In particular, the polymers of the invention provide for an extremely low water-to-cement or concrete ratio, high slump retention while maintaining good flowability, as well as low foam formation during the preparation of the cement or concrete.